Aim 1– To study diff types of networks. LAN - Local Area Network A LAN connects network devices over a relatively short distance. A networked office building, school, or home usually contains a single LAN, though sometimes one building will contain a few small LANs (perhaps one per room), and occasionally a LAN will span a group of nearby buildings. In TCP/IP networking, a LAN is often but not always implemented as a single IP subnet. In addition to operating in a limited space, LANs are also typically owned, controlled, and managed by a single person or organization. They also tend to use certain connectivity technologies, primarily Ethernet and Token Ring. WAN - Wide Area Network
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Aim 1– To study diff types of networks.
LAN - Local Area Network
A LAN connects network devices over a relatively short distance. A networked office building, school, or home
usually contains a single LAN, though sometimes one building will contain a few small LANs (perhaps one per
room), and occasionally a LAN will span a group of nearby buildings. In TCP/IP networking, a LAN is often
but not always implemented as a single IP subnet.
In addition to operating in a limited space, LANs are also typically owned, controlled, and managed by a single
person or organization. They also tend to use certain connectivity technologies, primarily Ethernet and Token
Ring.
WAN - Wide Area Network
As the term implies, a WAN spans a large physical distance. The Internet is the largest WAN, spanning the
Earth.
A WAN is a geographically-dispersed collection of LANs. A network device called a router connects LANs to a
WAN. In IP networking, the router maintains both a LAN address and a WAN address.
A WAN differs from a LAN in several important ways. Most WANs (like the Internet) are not owned by any
one organization but rather exist under collective or distributed ownership and management. WANs tend to use
technology like ATM, Frame Relay and X.25 for connectivity over the longer distances.
Metropolitan Area Network
It is a network spanning a physical area larger than a LAN but smaller than a WAN, such as a city. A MAN is
typically owned an operated by a single entity such as a government body or large corporation.
Aim 2- To study diff types topologies used in networking.
Topology Topology means how the computers/ nodes are physically connected to each other.
Bus topology
• Uses a trunk or backbone to which all of the computers on the network connect.
• Systems connect to this backbone using T connectors or taps.
• Coaxial cablings ( 10Base-2, 10Base5) were popular options years ago.
Bus Topology characteristics
-Does not use any specialized network to troubleshoot equipment.
-A break in the cable will prevent all systems from accessing the network.
-Require less cable
-Network disruption when computers are added or removed
-Cheap and easy to implement
Ring Topology • Logical ring
– Meaning that data travels in circular fashion from one computer to another on the network.
– Typically FDDI, SONET or Token Ring technology are used to implement a ring
– Ring networks are most commonly wired in a star configuration
• Token Ring has multi-station access unit (MSAU),equivalent to hub or switch. MSAU performs the token
circulation internally.
Ring Topology characteristics
-A single break in the cable can disrupt the entire network.
-Ring networks are moderately easy to install
-Expansion to the network can cause network disruption
-Cable faults are easily located, making troubleshooting easier
Star Topology • All computers/devices connect to a central device called hub or switch.
• Each device requires a single cable
• point-to-point connection between the device and hub.
• Most widely implemented
• Hub is the single point of failure
Star Topology characteristics
-More difficult
-Easy to troubleshoot and isolate to implement problems
-A central connecting device allows for a single point of failure
-Cable failure affects only a single user
-Easily expanded without disruption Requires more cable to the network
Mesh Topology
• Each computer connects to every other.
• High level of redundancy.
• Rarely used.
– Wiring is very complicated
– Cabling cost is high
– Troubleshooting a failed cable is tricky
– A variation hybrid mesh – create point to point connection between specific network devices, often seen in
WAN implementation.
Mesh Topology characteristics -Complicated
-The network can be expanded implementation without disruption to current uses
-Requires more cable than the other
-LAN topologies Provides redundant paths between devices
Aim 3: To study various types of guided transmission media in detail.
Transmission Media
Communication of data propagation and processing of signals is called transmission. Signals travel from
transmitter to receiver via a path. This path is called medium. Medium can be guided or unguided.
Twisted-Pair Copper Wire
The least-expensive and most commonly-used transmission medium is twisted-pair copper
wire. For over one-hundred years it has been used by telephone networks. In fact, more than
99% of the wired connections from the telephone handset to the local telephone switch use
twisted-pair copper wire. Most of us have seen twisted pair in our homes and work
environments. Twisted pair consists of two insulated copper wires, each about 1 mm thick,
arranged in a regular spiral pattern:. The wires are twisted together to reduce the electrical
interference from similar pairs close by. Typically, a number of pairs are bundled together in a
cable by wrapping the pairs in a protective shield. A wire pair constitutes a single
communication link.
Unshielded twisted pair (UTP)
It is commonly used for computer networks within a building, that is, for local area networks
(LANs). Data rates for LANs using twisted pair today range from 10 Mbps to 100 Mbps. The
data rates that can be achieved depend on the thickness of the wire and the distance between
transmitter and receiver. Two types of UTP are common in LANs: category 3 and category 5.
Category 3 corresponds to voice-grade twisted pair, commonly found in office buildings.Office
buildings are often prewired with two or more parallel pairs of category 3 twisted pair; one pair
is used for telephone communication, and the additional pairs can be used for additional
telephone lines or for LAN networking. 10 Mbps Ethernet, one of the most prevalent LAN
types, can use category 3 UTP. Category 5, with its more twists per centimeter and Teflon
insulation, can handle higher bit rates. 100 Mbps Ethernet running on category 5 UTP has
become very popular in recent years. In recent years, category 5 UTP has become common for
preinstallation in new office buildings. When fiber-optic technology emerged in the 1980s,
many people disparaged twisted-pair because of its relatively low bit rates. Some people even
felt that fiber optic technology would completely replace twisted pair. But twisted pair did not
give up so easily. Modern twisted-pair technology, such as category 5 UTP, can achieve data
rates of 100 Mbps for distances up to a few hundred meters. Even higher rates are possible over
shorter distances. In the end, twisted-pair has emerged as the dominant solution for high-speed
LAN networking.
Twisted-pair is also commonly used for residential Internet access. We saw that dial-up modem
technology enables access at rates of up to 56 Kbps over twisted pair. We also saw that ISDN is
available in many communities, providing access rates of about 128 Kbps over twisted pair. We
also saw that ADSL (Asymmetric Digital Subscriber Loop) technology has enabled residential
users to access the Web at rates in excess of 6 Mbps over twisted pair.
Coaxial-Cable
Like twisted pair, coaxial cable consists of two copper conductors, but the two conductors are
concentric rather than parallel. With this construction and a special insulation and shielding,
coaxial cable can have higher bit rates than twisted pair. Coaxial cable comes in two varieties:
baseband coaxial cable and broadband coaxial cable. Baseband coaxial cable, also called 50-
ohm cable, is about a centimeter thick, lightweight, and easy to bend. It is commonly used in
LANs; in fact, the computer you use at work or at school is probably connected to a LAN with
either baseband coaxial cable or with UTP. Take a look at the the connection to your computer's
interface card. If you see a telephone-like jack and some wire that resembles telephone wire,
you are using UTP; if you see a T-connector and a cable running out of both sides of the T-
connector, you are using baseband coaxial cable. The terminology "baseband" comes from the
fact that the stream of bits is dumped directly into the cable, without shifting the signal to a
different frequency band. 10 Mbps Ethernets can use either UTP or baseband coaxial cable. It is
a little more expensive to use UTP for 10 Mbps Ethernet, as UTP requires an additional
networking device, called a hub. Broadband coaxial cable, also called 75-ohm cable, is quite a
bit thicker, heavier, and stiffer than the baseband variety. It was once commonly used in LANs
and can still be found in some older installations. For LANs, baseband cable is now preferable,
since it is less expensive, easier to physically handle, and does not require attachment cables.
Broadband cable, however, is quite common in cable television systems.
With broadband coaxial cable, the transmitter shifts the digital signal to a specific frequency
band, and the resulting analog signal is sent from the transmitter to one or more receivers. Both
baseband and broadband coaxial cable can be used as a guided shared medium.
Specifically, a number of end systems can be connected directly to the cable, and all the end
systems receive whatever any one of the computers transmits.
Fiber Optics
An optical fiber is a thin, flexible medium that conducts pulses of light, with each pulse
representing a bit. A single optical fiber can support tremendous bit rates, up to tens or even
hundreds of gigabits per second. They are immune to electromagnetic interference, have very
low signal attenuation up to 100 kilometers, and are very hard to tap. These characteristics have
made fiber optics the preferred long-haul guided transmission media, particularly for overseas
links. Many of the long-distance telephone networks in the United States and elsewhere now
use fiber optics exclusively. Fiber optics is also prevalent in the backbone of the Internet.
However, the high cost of optical devices -- such as transmitters, receivers, and switches – has
hindered their deployment for short-haul transport, such as in a LAN or into the home in a
residential access network. AT&T Labs provides an excellent site on fiber optics, including
several nice animations.
Aim 4: To study various types of connectors used in computer networks.
Connectors used in Computer Networks –
A connector is best known for providing the physical link between two components. The use of a connector
might be a connector linking a cable and a network interface card or NIC card, a connector linking a transceiver
and a cable or even a connector linking two cable segments. There are various types of connectors used for
different transmission media such as –
1. RJ – 45
A registered jack (RJ) is a standardized physical network interface — both jack construction and wiring
pattern — for connecting telecommunications or data equipment to a service provided by a local
exchange carrier or long distance carrier.
The physical connectors that registered jacks use are mainly of the modular connector and 50-pin
miniature ribbon connector types.
RJ45 is a registered jack standard for a modular connector using 8 conductors, which specifies the
physical male and female connectors as well as the pin assignments of the wires in a telephone cable.
The "RJ45" physical connector is standardized as the IEC 60603-7 8P8C modular connector with
different "categories" of performance, with all eight conductors present but 8P8C is commonly known as
RJ45. The physical dimensions of the connectors are specified in ANSI/TIA-1096-A and ISO-8877
standards.
2. BNC
The BNC connector (Bayonet Neill–Concelman) is a common type of RF connector used for coaxial
cable. It is used with radio, television, and other radio-frequency electronic equipment, test instruments,
video signals, and was once a popular computer network connector. BNC connectors are made to match
the characteristic impedance of cable at either 50 ohms or 75 ohms. It is usually applied for frequencies
below 3 GHz and voltages below 500 Volts.
The BNC connector is used for signal connections such as:
1. analog and serial digital interface video signals
2. amateur radio antennas
3. aviation electronics (avionics)
4. test equipment.
3. SC Connector
SC stands for Subscriber Connector- a general purpose push/pull style Connector developed by NTT.
SC has an advantage in keyed duplexibility to support send/receive channels.
SC Connectors are frequently used for newer Network applications. The SC is a snap-in connector that
is widely used in singlemode systems for its performance. The SC connector is also available in a
Duplex configuration. They offer low cost, simplicity, and durability. SC connectors provide for
accurate alignment via their ceramic ferrules. The square, snap-in connector latches with a simple push-
pull motion and is keyed. They feature a 2.5mm Ferrule and molded housing for protection. Typical
matched SC connectors are rated for 1000 mating cycles and have an Insertion Loss of 0.25 dB.
4. ST Connector
ST stands for Straight Tip - a quick release bayonet style Connector developed by AT&T. STs were
predominant in the late 80s and early 90s.
ST Connectors are among the most commonly used Fiber optic connectors in networking applications.
They are cylindrical with twist lock coupling, 2.5mm keyed ferrule. ST Connectors are used both short
distance applications and long line systems. The ST connector has a bayonet mount and a long
cylindrical Ferrule to hold the fiber. Because they are spring-loaded, you have to make sure they are
seated properly. They are easily inserted and removed due to their design. If you experience high Light
loss, try reconnecting. ST connectors come in two versions: ST and ST-II. These are keyed and spring-
loaded. They are push-in and twist types. They are rated for 500 mating cycles. The typical Insertion
Loss for matched ST connectors is 0.25 dB.
5. MT-RJ Connector
MT-RJ stands for Mechanical Transfer Registered Jack. MT-RJ is a fiber-optic Cable Connector that
is very popular for small form factor devices due to its small size. Housing two fibers and mating
together with locating pins on the plug, the MT-RJ comes from the MT connector, which can contain up
to 12 fibers.
The MT-RJ is one of the newly emerging small form factor connectors that are becoming more common
in the networking industry. The MT-RJ utilizes two fibers and integrates them into a single design that
looks similar to a RJ45 connector. Alignment is completed through the use of two pins that mate with
the connector. Transceiver jacks found on NICs and equipment typically have the pins built into them.
The MT-RJ is commonly used for networking applications. Its size is slightly smaller than a standard
phone jack and just as easy to connect and disconnect. It's half the size of the SC Connector it was
designed to replace. The MT-RJ connector is a small form-factor Fiber optic connector which resembles
the RJ-45 connector used in Ethernet networks. Compared to single-fiber terminations such as SC, the
MT-RJ Connector offers lower Termination cost and greater density for both electronics and cable
management hardware. The MT-RJ Connector is significantly lower in cost and smaller in size than the
SC Duplex interface. The small MT-RJ Interface can be spaced the same as copper, effectively doubling
the number of fiber ports. The net effect is a Drop in the overall price per fiber Port making fiber-to-the-
desktop solutions more competitive with copper
Aim 5: To study diff. types of protocols in tcp/ip suit
TCP/IP Protocol Suite
The TCP/IP model is a descriptive framework for computer network protocols created in the 1970s by DARPA,
an agency of the United States Department of Defense. The name derives from the two most important
protocols of the networking protocol suite, the Transmission Control Protocol (TCP) and the Internet Protocol
(IP). The model evolved from the operational principles of the ARPANET, which was an early wide area
network and a predecessor of the Internet. The TCP/IP model is formalized in the Internet protocol suite and is
sometimes called the Internet model or the DoD model.
The TCP/IP model describes a set of general design guidelines and implementations of specific networking
protocols to enable computers to communicate over a network. TCP/IP provides end-to-end connectivity
specifying how data should be formatted, addressed, transmitted, routed and received at the destination.
Protocols exist for a variety of different types of communication services between computers.
TCP/IP has four abstraction layers as defined in RFC 1122, The TCP/IP model and related protocols are
maintained by the Internet Engineering Task Force (IETF).
User Datagram Protocol
The User Datagram Protocol is very simple. The PDU used by UDP is called a datagram. Datagrams are
considered unreliable,in that there is no guarantee datagrams will be received in the correct order, if at all. If
reliability of the information transmitted is needed, UDP should not be used.While UDP is unreliable, the lack
of error checking and correction make UDP fast and effic -ient for many less data intensive or timesensitive
applications, such as the Domain Name Service (DNS), the Simple Network Management Protocol (SNMP),
the Dynamic Host Configuration Protocol (DHCP) and the Routing InformationProtocol (RIP). UDP is also
well suited for streaming video.
Transmission Control Protocol
In the TCP/IP protocol suite, TCP is the intermediate layer between IP below it, and an application above it.
Using TCP, applications on networked hosts can establish reliable connections to one another. The protocol
guarantees in-order delivery of data from the sender to the receiver. Both tcp and udp works on port no.from
range.0-32768.
TCP connections have three phases:
1. Connection establishment
2. Data transfer
3. Connection termination
• File Transfer Protocol (FTP)— It works on port no.21. Provides a mechanism for moving data files between
systems. The FTP client and server programs, as well as most Web browsers, contain an implementation of the
FTP protocol.
• HyperText Transfer Protocol (HTTP)— It works on port no. 80.Protocol used to move Web pages across
an internet connection. The HTTP protocol is built into Web browsers and Web servers.
• Interactive Mail Access Protocol (IMAP)— It works on port no. 143.Provides clients access to e-mail
messages and mailboxes over a network. It is incorporated into e-mail applications.
• Post Office Protocol (POP)— It works on port no. 110.Allows clients to read and remove e-mail residing on
a remote server. It is incorporated into e-mail applications.